This proposal relates to problems that effect the long term survival of total joint prostheses. Carcinogeneses studies of the currently used metal alloys and polymers in solid and metal form are conducted. The metal fatigue includes the evaluation of 316L stainless steel, cast cobalt chrome and the newly applied high strength alloys. The wear of UHMW polyethylene, Delrin 150, the relation between wear of UHMW polyethylene and its molecular and crystaline structure and the creep characteristics of wear resistant polymers are investigated. Finite element techniques are used to study stress analysis of total hip prostheses. The studies include modeling of the upper end of the femur to study stress distribution in surface replacement, the development of interface models to study the stresses at the bone-cement and cement-prosthesis interface and the evaluation of stress distribution in different types of prosthetic stems. Other studies have included in vivo crevice corrosion and the retrospective analysis of retrieved failed devices.